Now Have I got an answer for you after recently deciding Hey I want to play this game (Because of projared) I have found out how to play the game (Some help from out of date (I assume) posts. I have found a fix for you. So Download the enders Thingy... https://github.com/EnderWiggin/haven-updater/releases
That is it You can begin your quest to starting the game so once you have updated the stuff your instinct is to use the file that the updater provided named Haven. To your surprise that failed (Because it is impossible to log in this way), so what does it? Clicking the updater file... Yes the updater file opens the game after checking the updates and opens the game automatically this actually the only way I have been able to play this game. Now I have noticed that some people have been able to open the game without this method but this is the only way I have been able to open it so... I hope this helps.